This invention relates to a lighting system, which may be used, for example, as an airport lighting system, as a street lighting system, as an obstruction light, as an illuminated sign, as a warning light, or as a signal light or the like.
German Patent DE-A-42 32 618 and International reference WO 90/04242 A teach a lighting system, which includes a unit for monitoring and controlling light sources or groups of light sources of a lighting system. These light sources may be designed as blister lights. Each of these light sources has at least one lighting unit. This lighting unit is associated with a transceiver device, which is equipped with a microcontroller. Via the power supply line of the lighting system, the transceiver device is connected with a central station, which can selectively control the microcontroller of the respective transceiver device. For this purpose, the central station is equipped with a transceiver unit and a control computer. The microcontroller of each lighting unit is part of a decentralized control device, which includes application-specific components, e.g., switching elements, monitoring elements, and adjusting elements. In addition, in the lighting system disclosed in WO 90/04242 A, each transceiver device is embodied as a module part. This module part includes switching components and monitoring components, which are connected upstream from the microcontroller and the lighting unit of the blister light.
A similar lighting system is disclosed in European Patent EP-A-0 723 384. This lighting system is designed as a safety lighting system, wherein, in case of a power failure, the individual light sources of the lighting system are supplied with battery power. For this purpose, each of the light sources or each group of light sources is associated with a change-over switch device. In case of a power failure, the change-over switch device permits a switch over to battery operation. In this safety lighting system, the change-over switch devices of the light sources or of the groups of light sources are part of a decentralized control unit. Therein, the control unit includes power-on elements, power-off elements, and monitoring elements.
European Patent EP-A-0 900 882 discloses a lighting system, which includes blister lights and which is intended for traffic control. In these blister lights, light emitting diodes are used as the lighting unit. Via connection leads, each individual light emitting diode is connected to a printed circuit board, which is arranged at a location remote from the light emitting diodes. Furthermore, drive components are provided in the blister lights, which drive the light emitting diodes.
U.S. Pat. No. 4,924,364 discloses a blister light for airports. Therein, the lighting unit is an electric lamp, which, together with the optical unit of the blister light, can be separated from the remaining components of the blister light. For this purpose, an optical block, which includes the electric lamp, is vertically removed from the blister light.
It is one object of the present invention to improve a lighting system, such as the one known from the above referenced WO 90/04242 A, so as to permit a more compact design of the blister lights or of the light sources.
This and other objects are achieved by a lighting system, which includes a plurality of blister lights, which, in turn, have at least one respective lighting unit. The lighting system furthermore includes a device for monitoring and controlling the blister lights. A transceiver device, which includes a microcontroller, is associated with the lighting unit. In addition, the system includes a central station, which has a transceiver part and a control computer. The central station is connected to the transceiver device via a power supply line and a router and is configured to supply control commands to the transceiver device. The microcontroller is structured as a component of a decentralized control device, which includes application-specific components. Each transceiver device is structured as a module part; wherein the module part has switching components and monitoring components, which are connected upstream from the microcontroller and the lighting unit of the blister light. The switching components and the monitoring components of the module part are disposed on a sickle-shaped printed circuit board. The module part is disposed next to the lighting unit and at the same level as the lighting unit of the blister light.
The inventive embodiments of the printed circuit board and the arrangement of the module part at the level of the lighting unit allow for a flatter design of the blister lights or light sources than achieved in the prior art.
Lighting systems according to the invention are well suited for small airports, heliports, mobile airport equipment, field airstrips, landing places or the like. In addition, the lighting system according to the invention is advantageously applied in street lighting systems, e.g., to indicate temporary traffic lane changes or the like.
If the lighting unit of the lighting s stem according to the invention is formed by a plurality, or a cluster, of light emitting diodes (LEDs), the power supply of the individual lighting units can be reduced. The life span of the lighting units thus designed is significantly increased, so that the maintenance intervals of the lighting system are increased too. This results in significantly reduced maintenance costs. Due to the lower power consumption and maintenance expenditure, the lighting systems according to the invention can be operated much more cost-effectively than conventional lighting systems of this type. As an alternative to the embodiment of the lighting units as light emitting diodes (LEDs), the lighting units may also be formed by light emitting polymers, which provide similar advantages.
To further reduce the technological complexity for controlling and monitoring the lighting systems according to the invention, it is advantageous if the decentralized control units of the lighting system are designed as a LON (Local Operating Network).
In a preferred embodiment of the invention, the microcontroller is designed as a one-chip controller, which provides significant savings with respect to the technical-structural complexity and with respect to costs.
The microcontroller advantageously includes an EEPROM; a RAM; three CPUs; a clocking-and-control-block, which has clock/timer elements; an application input/output block; and a communications port. The EEPROM, the RAM, the three CPUs, the application input/output block, and the communications port are interconnected by means of an internal address bus and by means of an internal data bus. The EEPROM, the RAM, the three CPUs, the application input/output block, the communications port, and the clocking-and-control-block are interconnected by means of a timing-and-control circuit.
Advantageously, the EEPROM of the microcontroller has a memory capacity of 512 bytes and is capable of storing network parameters and application programs.
It is advantageous, if each of the three CPUs of the microcontroller is designed as an 8-bit CPU. Thereby, one of the three CPUs of the microcontroller can be used for application programs.
The two other CPUs of the microcontroller can be used for LONTALK protocol processing, wherein the processable protocols include all seven layers of a reference model in accordance with ISO/OSI standards.
The application input/output block can advantageously be used as a parallel interface to an external microprocessor, which has eight data lines and three control lines.
According to one embodiment of the invention, the application input/output block of the microcontroller has a 16-bit load register, a counter, a buffer memory (latch), a clock source, four 20 mA sink current pins, four programmable pull-ups, and possibly additional elements.
The communications port of the microcontroller is advantageously provided with five network interface pins to connect the microcontroller to a base band medium, e.g., to a two-wire cable, or to an external transceiver.
The microcontroller can have a low voltage detector circuit and a low voltage reset circuit to prevent faulty operation or malfunctions of the EEPROM if the applied voltage is lower than 4.1 VDC+/xe2x88x92300 mV tolerance.
If the microcontroller does not have a ROM, it is advantageous to equip the microcontroller with an external memory interface. In this case, the RAM of the microcontroller can advantageously have a memory capacity of 2048 bytes.
According to a further embodiment of the invention, the microcontroller has a RAM with a memory capacity of 1024 bytes or 2048 bytes and a ROM with a memory capacity of 10240 bytes.
Each microcontroller has an unambiguous, non-erasable identification number to link the respective function state of the lighting unit with an address that has preferably 48 bits and for which the 6 bytes of the EEPROM can be used.
Advantageously, the microcontroller has a service pin to permit an effective network installation.
In a preferred embodiment of the invention, each blister light has a light intensity regulating circuit, which sets a predetermined desired lighting-means-current-value via a pulse width modulation element and which readjusts the actual value.
It is advantageous if this light intensity regulating circuit is implemented for load-dependent compensation and for line-length compensation of the dropout voltage or the voltage drop.
It is advantageous if a switching power supply is provided, which has a toroidal-core transformer as an isolating element. The toroidal-core transformer, together with the pulse width modulation element, determines the transmitted power.
In addition, it is advantageous to provide each blister light with an isolation circuit, which produces a rapid isolation between the transceiver device and the power supply line if unacceptable currents occur. In addition, the isolation circuit terminates this isolation after the disturbance has been repaired, e.g. through replacement of the lighting unit.
A measurement circuit is provided, via which an isolation and a reconnection can be detected by the microcontroller.
It is advantageous if, via the measurement circuit, all lighting units functions are detected and input into the microcontroller, where the actual lighting unit values are compared with the desired lighting unit values.
If light emitting diodes (LED) are used for the blister lights, it is advantageous if each blister light has a supply circuit, by means of which the lighting unit current is adjusted to the supply voltage.
It is advantageous if each blister light has a regulator circuit, whereby a signal can be generated by means of which the actual functional state of the lighting unit is fed back to the central station via the power supply line. Such an actual functional state of the lighting unit can be, for example, a lighting unit defect, a line interruption, or a short-circuit.
In another preferred embodiment of the present invention, each blister light is provided with a further supply circuit for the microcontroller, which guarantees that, in case of defects in the lighting circuit, a differentiated message is transmitted to the LON.
In an advantageous embodiment of the invention, functional data on the state of the individual circuits of a respective transceiver device are reported to the central station by means of the microcontroller. This leads to considerable savings in maintenance and repair.
To further facilitate maintenance and repair, it is advantageous for the individual blister lights to be detachably connected by a cable to the main power supply line. In particular, such a detachable connection is preferably a watertight first plug connection, which is preferably implemented as an earthed plug connection.
The lighting unit of the blister light can include an internal second plug connection, which is preferably implemented as a two-pole FAA plug connection. By means of the internal second plug connection, the lighting unit is connected to upstream elements of the blister light.
Advantageously, the individual blister lights are removable from their seats below ground and can be isolated from the main power supply line by means of the first plug connection.
The association of individual blister lights with predetermined blister light groups or blister light chains, which association can be configured via the power supply line, ensures great variability and adjustability of the airport lighting system or street lighting system to various requirements.
To provide conformity with standards used in Europe, communication on the power supply line should be performed in the C-band in accordance with CENELEC.
It is advantageous if the blister lights are parallel-connected to the power supply line.
To simplify the assembly of the blister lights, the microcontroller and the additional switching components and monitoring components, which are connected upstream from the lighting unit of each blister light, are positioned on a printed circuit board. This printed circuit board is adapted to the shape of a housing of the blister light and is fastened in the blister light in a shock-proof and vibration-proof manner.
For this purpose, it is advantageous if the module part of each blister light is connected to the power supply line by means of the detachable first plug connection, and if the module part of each blister light is connected to the lighting unit of the blister light by means of the internal plug connection. Therein, the detachable first plug connection is preferably implemented as a watertight connection.
To avoid interference in the received signal, it is advantageous if the module part of each blister light has a metallic, grounded housing.
To prevent moisture from penetrating into the module part, which could lead to malfunctions of the blister light, it is advantageous if the module part is watertight-embedded in plastic, for example. In this case, an unconnected cable end is provided for each of the two plug connections.
The lighting system according to the invention allows for almost potential-free operation of the blister lights with minimal power consumption. In standby operation, the power consumption is even further reduced.